Electroluminescent devices and methods

ABSTRACT

Electroluminescent devices, and methods of making and using such devices, are disclosed. The electroluminescent devices include a patterned layer on a solvent-susceptible layer. The electroluminescent devices may be used, for example, as full color display devices.

BACKGROUND

The formation of patterned light emitting layers is an important butdifficult step in the production of electroluminescent devices. Forexample, the formation of separate red, green and blue patterned emitterlayers is typically required in the production of electroluminescentfull color display devices. Vacuum evaporation (e.g., using a shadowmask) is the most common technique to form each of the patterned layers.Because of the complexity and cost of this technique, particularly foruse in making large format displays, other methods of forming patternedlayers are needed in the art. Methods based on depositing materials fromsolution are especially desirable for their expected compatibility withlarge scale device fabrication.

Ink jet printing techniques have been suggested for producing patternedemitter layers. Depositing two colors of patterned emitter precursors byink jet printing, followed by depositing a third color of emitter bysolution techniques has been reported. However, the use of ink jetprinting techniques to deposit patterned layers is limited by factorsincluding solubility, wetting, and uniformity of the materials beingdeposited in the ink jet media.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a method of making anelectroluminescent device. In one embodiment, the method includes:selectively thermally transferring a portion of a transfer layerincluding a first emitter to a receptor, which is optionallysolvent-susceptible, to form a patterned emitter layer including thefirst emitter disposed on the receptor; and disposing a layer includinga second emitter on the patterned emitter layer and the receptor to forma non-patterned emitter layer including the second emitter. Optionally,the method further includes selectively thermally transferring, prior toforming the non-patterned emitter layer, a portion of a second transferlayer including a third emitter to the receptor to form a secondpatterned emitter layer including the third emitter, disposed on thereceptor. Preferably, the receptor is an anode, a hole transport layer,a hole injection layer, an electron blocking layer, a dielectric layer,a passivation layer, a substrate, or a combination thereof. Preferably,the non-patterned emitter layer is an undoped electron transport layer,a doped electron transport layer, an undoped hole blocking layer, adoped hole blocking layer, or a combination thereof. In someembodiments, the receptor is a hole transport layer and is attached toan anode, in which case the device can optionally include a holeinjection layer disposed between the hole transport layer and the anode.Optionally, the method further includes disposing a cathode on thenon-patterned emitter layer.

In another embodiment, the method of making an electroluminescent deviceincludes: providing a non-patterned layer including a first emitter; andselectively thermally transferring a portion of a transfer layerincluding a second emitter to the non-patterned emitter layer, which isoptionally solvent-susceptible, to form a patterned emitter layerincluding the second emitter, disposed on the non-patterned emitterlayer. Optionally, the method further includes selectively thermallytransferring a portion of a second transfer layer including a thirdemitter to the non-patterned emitter layer to form a second patternedemitter layer including the third emitter, disposed on the non-patternedemitter layer. Preferably, the non-patterned emitter layer is an undopedelectron transport layer, a doped electron transport layer, an undopedhole blocking layer, a doped hole blocking layer, an undoped electroninjecting layer, a doped electron injecting layer, or a combinationthereof. In some embodiments, the method further includes disposing ananode on the patterned emitter layer and the non-patterned emitterlayer. A hole transport layer, a hole injection layer, an electronblocking layer, or a combination thereof, can optionally be disposedbetween the emitter layers and the anode. Optionally, the side of thenon-patterned emitter layer opposite the patterned emitter layer isattached to a cathode.

In another embodiment, the method of making an electroluminescent deviceincludes: providing a solvent-susceptible layer; disposing a patternedlayer including a first emitter and a non-volatile component that is thesame as or different than the first emitter on the solvent-susceptiblelayer; and disposing a layer including a second emitter on the patternedlayer and the solvent-susceptible layer to form a non-patterned emitterlayer including the second emitter. Preferably, disposing the patternedlayer includes selectively thermally transferring a portion of atransfer layer including the first emitter and the non-volatilecomponent. Optionally, prior to forming the non-patterned emitter layer,a second patterned layer including a third emitter is disposed on thesolvent-susceptible layer, preferably by thermally transferring aportion of a second transfer layer including the third emitter and,optionally, a non-volatile component.

In another embodiment, the method of making an electroluminescent deviceincludes: providing a solvent-susceptible, non-patterned layer includinga first emitter; and disposing a patterned layer including a secondemitter and a non-volatile component that is the same as or differentthan the second emitter on the solvent-susceptible layer. Preferably,disposing the patterned layer includes selectively thermallytransferring a portion of a transfer layer including the second emitterand the non-volatile component. Optionally, the method further includesdisposing a second patterned layer including a third emitter and,optionally, a non-volatile component, on the solvent-susceptible layer,preferably by thermally transferring a portion of a second transferlayer including the third emitter.

In another aspect, the present invention provides an electroluminescentdevice. The electroluminescent device includes: a solvent-susceptiblelayer; a patterned layer on the solvent-susceptible layer, wherein thepatterned layer includes a first emitter and a non-volatile componentthat is the same as or different than the first emitter; and anon-patterned layer including a second emitter disposed on the patternedemitter layer and the solvent susceptible layer. Optionally, thepatterned layer further includes a third emitter. Alternatively, asecond patterned layer may optionally be disposed on thesolvent-susceptible layer, wherein the second patterned layer includes athird emitter. Preferably, the solvent-susceptible layer is a holetransport layer, a hole injection layer, an electron blocking layer, adielectric layer, a passivation layer, or a combination thereof.Preferably, the non-patterned emitter layer is an undoped electrontransport layer, a doped electron transport layer, an undoped holeblocking layer, a doped hole blocking layer, an undoped electroninjecting layer, a doped electron injecting layer, or a combinationthereof. In some embodiments, an anode can be attached to thesolvent-susceptible layer and a cathode can be attached to thenon-patterned emitter layer. Optionally, a hole injection layer, anelectron blocking layer, or a combination thereof can be disposedbetween the anode and the solvent-susceptible layer. In one embodiment,the cathode is opaque, the anode is transparent, and the device isoperable to emit light through the transparent anode. In anotherembodiment, the cathode is transparent, the anode is opaque, and thedevice is operable to emit light through the transparent cathode. Instill another embodiment, the cathode is transparent, the device furtherincludes an opaque substrate attached to the anode, and the device isoperable to emit light through the transparent cathode. In yet anotherembodiment, the cathode is transparent, the anode is transparent, andthe device is operable to emit light through the transparent cathode andthe transparent anode. Optionally, the non-patterned emitter layer issolvent-susceptible.

In another aspect, the present invention provides a method of generatinglight. The method includes: providing an electroluminescent device asdescribed herein; and providing a signal to the anode and the cathode,wherein the signal is operable to address an emitter, following whichthe emitter emits light. Preferably, the device is an active or passiveaddressed device. Preferably, the device is a full color display ortunable lighting device.

The emission characteristics of a multilayered OLED device can bealtered by controlling or confining the zone in which the recombinationof electrons and holes occurs. For a device with a single layer capableof efficient fluorescent or phosphorescent emission, the optimum deviceperformance occurs when the recombination zone is located within theemitter layer. For a device with multiple emission layers (e.g. a redpatterned emitter layer and a blue non-patterned emitter layer), it ispossible to obtain emission predominantly from a single layer (e.g. thered patterned emitter layer). Therefore, it is possible to construct afull-color OLED display by, for example, patterning a substrate with redand green emitting regions and then providing a non-patterned blueemitter layer. If the recombination zone is controlled properly, the redand green emitting regions will not exhibit a significant blue emission.For display device applications, it is preferably to have displaysubpixels that emit saturated red, green, and blue colors. Therefore, inembodiments of the present invention in which patterned emitter layersare formed by selectively thermally transferring portions of emitterlayers, it is possible to prepare an “n” color device (e.g., a threecolor device) by using fewer than “n” thermal transfer steps (e.g., twoselective thermal transfer steps).

In some embodiments, it is possible, and sometimes preferable to alterthe amount of emission from different layers of a multilayer device byvarying the operating voltage or current density. This so-called “colortuning” can be useful for OLEDs used in lighting applications.

Definitions

As used herein, a “layer” refers to a discontinuous (e.g., a patternedlayer) or continuous (e.g., non-patterned) material disposed on anothermaterial.

As used herein, a “patterned layer” refers to a discontinuous layer inwhich the material of the patterned layer is disposed on only selectedportions of the other material.

As used herein, a “non-patterned layer” refers to a continuous layer inwhich the material of the non-patterned layer is disposed on an entireportion of the other material.

As used herein, a “solvent-susceptible” layer is a layer that would bedissolved, attacked, penetrated, and/or rendered inoperable for itsintended purpose in the presence of a solvent, had a solvent-coatedlayer been coated directly on the solvent-susceptible layer.

As used herein, a “solvent” for a solvent-coated layer refers to anorganic or an aqueous solvent that is capable of dissolving, dispersing,or suspending an organic polymer or resin that is suitable to form alayer of an electroluminescent device.

In general, a layer “disposed on” or “attached to” another layer isintended to be broadly interpreted to optionally include one or moreadditional layers between the two layers.

As used herein, a layer “on” or “disposed on” a “solvent-susceptiblelayer” is intended to include either a layer that is directly in contactwith the solvent-susceptible layer, or a layer that is separated by oneor more additional layers from the solvent-susceptible layer, with theproviso that solvent from the layer “on” or “disposed on” thesolvent-susceptible layer would be capable of coming in contact with thesolvent-susceptible layer (e.g., through vaporization, diffusion, orother methods of transporting the solvent through the additionallayers). Preferably, a layer “on” or “disposed on” a“solvent-susceptible layer” is in direct contact with thesolvent-susceptible layer.

As used herein, “transparent electrode” means a conductive element thatsubstantially transmits visible light. An element that substantiallytransmits visible light preferably transmits at least 50%, and morepreferably at least 80%, of incident visible light, particularly at thewavelengths corresponding to the device emission maxima, impinged normalto the surface of the element.

As used herein, “opaque electrode” means a conductive element thatsubstantially absorbs or reflects visible light. An element thatsubstantially absorbs or reflects visible light preferably absorbs orreflects at least 90% of incident visible light, particularly at thewavelengths corresponding to the device emission maxima, impinged normalto the surface of the element.

As used herein, an “active addressed” device is a device that includes ascheme for driving an array of pixels or subpixels, wherein each pixelor subpixel is addressed by a discrete circuit. Generally, the discretecircuit is adjacent to the pixel or subpixel and internal to the device.

As used herein, a “passive addressed” device is a device that includes ascheme for driving an array of pixels or subpixels, wherein each pixelor subpixel is addressed through electronic circuitry that includes rowand column electrodes. Generally, the electronic circuitry is externalto the device.

As used herein, “tunable lighting” device is an element that emits lightof a variable color dependent upon the driving conditions (e.g. voltage,current density, etc.).

As used herein, “full color display” device means an electroniccomponent comprising an array of pixels and subpixels that is capable ofdisplaying an image with a color gamut suitable for portraying colorphotographs and videos (e.g. the gamut defined by the NationalTelevision Standards Committee NTSC).

As used herein, “non-volatile component” means a component with anegligible vapor pressure under the conditions typically used for vacuumevaporation or vacuum sublimation. Typically, a material that cannot bedeposited at a rate of at least 0.1 Angstroms/second at a temperaturebelow its decomposition temperature, is considered to be non-volatile.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A to 1C are schematic cross-sectional views illustrating anexemplary method of assembling electroluminescent devices according tothe invention and having a “bottom anode” configuration. The methodsillustrated in FIGS. 1A to 1C are illustrated in a simplified manner toexemplify preferred embodiments of the present invention. The inclusionof an additional layer or layers that would be desirable in theconstruction of specific devices would be obvious to one of skill in theart. Thus, the methods and devices illustrated herein are not intendedto be limited solely to the specific layers described herein, but shouldbe broadly interpreted as including additional layers as desired.

FIGS. 2A to 2C are schematic cross-sectional views illustrating anexemplary method of assembling electroluminescent devices according tothe invention and having a “top anode” configuration. The methodsillustrated in FIGS. 2A to 2C are illustrated in a simplified manner toexemplify preferred embodiments of the present invention. The inclusionof an additional layer or layers that would be desirable in theconstruction of specific devices would be obvious to one of skill in theart. Thus, the methods and devices illustrated herein are not intendedto be limited solely to the specific layers described herein, but shouldbe broadly interpreted as including additional layers as desired.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides electroluminescent devices, and methodsof making and using such devices. Electroluminescent devices are wellknown in the art and include, for example, organic electroluminescent(OEL) devices. See, for example, Salbeck, Ber. Bunsenges. Phys. Chem.,100(10): 1667 (1996); Y. Sato, “Organic LED System Considerations” inSemiconductors and Semimetals (G. Meuller, ed.), Vol. 64, p. 209 (2000);Kido, Bulletin of Electrochemistry, 10(1):1 (1994); F. So et al.,International Journal of High Speed Electronics and Systems, 8(2):247(1997); Baldo et al., Pure Appl. Chem., 71(11):2095 (1999). As usedherein, “electroluminescent device” is meant to encompass complete andpartial devices (e.g., device components). Similarly, methods of makingelectroluminescent devices are meant to encompass the formation orpartial formation of devices or device components.

A layer or layers of an electroluminescent device may be formed viathermal transfer of a layer or layers from a thermal transfer donorelement. As a particular example, a thermal transfer element can beformed for making, at least in part, an OEL device or array of devices,and components for use in OEL displays. This can be accomplished, forexample, by thermal transfer of a single or a multicomponent transferunit of a thermal transfer element. It will be recognized that singlelayer and multilayer transfers can be used to form other devices andobjects. While the present invention is not so limited, an appreciationof various aspects of the invention will be gained through a discussionof the examples provided below.

Materials can be patterned onto substrates by selective thermal transferof the materials from one or more thermal transfer elements. A thermaltransfer element can be heated by application of directed heat on aselected portion of the thermal transfer element. Heat can be generatedusing a heating element (e.g., a resistive heating element), convertingradiation (e.g., a beam of light) to heat, and/or applying an electricalcurrent to a layer of the thermal transfer element to generate heat. Inmany instances, thermal transfer using light from, for example, a lampor laser, is advantageous because of the accuracy and precision that canoften be achieved. The size and shape of the transferred pattern (e.g.,a line, circle, square, or other shape) can be controlled by, forexample, selecting the size of the light beam, the exposure pattern ofthe light beam, the duration of directed beam contact with the thermaltransfer element, and the materials of the thermal transfer element.

A thermal transfer element can include a transfer layer that can be usedto form various elements and devices, or portions thereof. Exemplarymaterials and transfer layers include those that can be used to formelements, devices, and portions thereof that are useful in electronicdisplays. While the examples used in the present invention most oftenfocus on OEL devices and displays, transfer of materials from thermaltransfer elements can also be used to form, at least in part, electroniccircuitry and optical and electronics components such as resistors,capacitors, diodes, rectifiers, electroluminescent lamps, memoryelements, field effect transistors, bipolar transistors, unijunctiontransistors, MOS transistors, metal-insulator-semiconductor transistors,organic transistors, charge coupled devices, insulator-metal-insulatorstacks, organic conductor-metal-organic conductor stacks, integratedcircuits, photodetectors, lasers, lenses, waveguides, gratings,holographic elements, filters (e.g., add-drop filters, gain-flatteningfilters, cut-off filters, and the like), mirrors, splitters, couplers,combiners, modulators, sensors (e.g., evanescent sensors, phasemodulation sensors, interferometric sensors, and the like), opticalcavities, piezoelectric devices, ferroelectric devices, thin filmbatteries, or a combination thereof; for example, the combination offield effect transistors and organic electroluminescent lamps as anactive matrix array for an optical display. Other items may be formed bytransferring a multicomponent transfer unit and/or a single layer.

Thermal transfer using light can often provide better accuracy andquality control for very small devices, such as small optical andelectronic devices, including, for example, transistors and othercomponents of integrated circuits, as well as components for use in adisplay, such as electroluminescent lamps and control circuitry.Moreover, thermal transfer using light may, at least in some instances,provide for better registration when forming multiple devices over anarea that is large compared to the device size. As an example,components of a display, which has many pixels, can be formed using thismethod.

In some instances, multiple thermal transfer elements may be used toform a device or other object, or to form adjacent devices, otherobjects, or portions thereof. The multiple thermal transfer elements mayinclude thermal transfer elements with multicomponent transfer units andthermal transfer elements that transfer a single layer. For example, adevice or other object may be formed using one or more thermal transferelements with multicomponent transfer units and/or one or more thermaltransfer elements that each can be used to transfer a single layer or amultilayer unit.

Thermal transfer of one or more layers to form a device or an array ofdevices can also be useful, for example, to reduce or eliminate wetprocessing steps of processes such as photolithographic patterning orink-jet patterning, which are used to form many electronic and opticaldevices. Thermal transfer to pattern layers from donor elements can alsobe useful to de-couple layer coating steps from patterning steps, forexample where such coupling can limit the types of layered structures,or the types of adjacent structures, that can be patterned. Inconventional patterning processes such as photolithography, ink-jet,screen printing, and various mask-based techniques, layers are typicallycoated directly onto the substrate on which patterning occurs.Patterning can take place simultaneously with coating (as for ink-jet,screen printing, and some mask-based processes) or subsequent to coatingvia etching or another removal technique. A difficulty with suchconventional approaches is that solvents used to coat materials, and/oretching processes used to pattern materials, can damage, dissolve,penetrate, and/or render inoperable previously coated or patternedlayers or materials.

In the present invention, materials can be coated onto thermal transferdonor elements to form the transfer layers of the donor elements. Thetransfer layer materials can then be patterned via selective thermaltransfer from the donor to a receptor. Coating onto a donor followed bypatterning via selective transfer represents a de-coupling of layercoating steps from patterning steps. An advantage of de-coupling coatingand patterning steps is that materials can be patterned on top of ornext to other materials that would be difficult to pattern, if possibleat all, using conventional patterning processes. For example, in methodsof the present invention a solvent-coated layer can be patterned on asolvent-susceptible material that would be dissolved, attacked,penetrated, and/or rendered inoperable for its intended purpose in thepresence of the solvent had the solvent-coated layer been coateddirectly on the solvent-susceptible material. The same holds forpatterned thermal transfer of solvent-coated materials next to, but notnecessarily in contact with, materials or layers on a receptor that maybe incompatible with the solvent.

A “solvent-susceptible” layer is a layer that would be dissolved,attacked, penetrated, and/or rendered inoperable for its intendedpurpose in the presence of a solvent, had a solvent-coated layer beencoated directly on the solvent-susceptible layer. A simple test forsolvent susceptibility is performed by spin coating a first layer from afirst solvent, drying the solvent, and then spin coating a secondsolvent on top of the first coated layer. If the first coated layer isdissolved, attacked, or penetrated by the second solvent, then the firstcoated layer is considered to be a solvent-susceptible layer.Alternatively, a similar test can be performed when the first coatedlayer has been deposited by vacuum evaporation.

The “second solvent” is preferably an organic solvent that is capable ofdissolving, dispersing, or suspending an organic polymer or resin thatis suitable to form a layer of an electroluminescent device. Suitablesolvents can be found, for example, in I. M. Smallwood, “Handbook ofOrganic Solvent Properties”, Arnold/Halsted Press (1996).

In some embodiments of the present invention, the transfer layer willinclude a non-volatile component. A non-volatile component is a chemicalcompound with a negligible vapor pressure under conditions typicallyused for vacuum evaporation or vacuum sublimation. A simple test fordetermining whether a compound is non-volatile is to attempt to sublimethe compound under vacuum deposition conditions for that component.Non-volatile compounds generally decompose (e.g. char, degrade, etc.) orfail to sublime at a rate sufficient to be practical for vacuumdeposition in currently available vacuum deposition systems. Typically,materials which cannot achieve a deposition rate of at least 0.1Angstroms/second at a temperature below their decomposition temperature,can be considered to be non-volatile. Common examples of non- volatilecomponents include polymers, oligomers, dendrimers, large molecularweight species, ceramics, etc.

As will be discussed in more detail below, the formation of OEL devicesprovides particularly suited examples. Exemplary donor elements, thermaltransfer methods, and devices made by thermal transfer methods aredisclosed, for example, in U.S. Pat. No. 6,410,201 (Wolk et al.).

For thermal transfer using radiation (e.g., light), a variety ofradiation-emitting sources can be used in the present invention. Foranalog techniques (e.g., exposure through a mask), high-powered lightsources (e.g., xenon flash lamps and lasers) are useful. For digitalimaging techniques, infrared, visible, and ultraviolet lasers areparticularly useful. Suitable lasers include, for example, high power(≧100 millwatts (mW)) single mode laser diodes, fiber-coupled laserdiodes, and diode-pumped solid state lasers (e.g., Nd:YAG and Nd:YLF).Laser exposure dwell times can be in the range from, for example, 0.1 to100 microseconds and laser fluences can be in the range of, for example,0.01 to 1 joules per centimeter squared (J/cm²).

When high spot placement accuracy is required (e.g. for high informationfull color display applications) over large substrate areas, a laser isparticularly useful as the radiation source. Laser sources arecompatible with both large rigid substrates such as 1 m×1 m×1.1 mmglass, and continuous or sheeted film substrates, such as 100 micrometerpolyimide sheets.

Resistive thermal print heads or arrays may be used, for example, withsimplified donor film constructions that may lack a light to heatconversion (LTHC) layer or a radiation absorber. This may beparticularly useful with smaller substrate sizes (e.g., less thanapproximately 30 cm in any dimension) or for larger patterns, such asthose required for alphanumeric segmented displays.

During imaging, the thermal transfer element is typically brought intointimate contact with a receptor. In at least some instances, pressureor vacuum are used to hold the thermal transfer element in intimatecontact with the receptor. A radiation source is then used to heat theLTHC layer (and/or other layer(s) containing radiation absorber) in animagewise fashion (e.g., digitally or by analog exposure through a mask)to perform imagewise transfer of the transfer layer from the thermaltransfer element to the receptor according to a pattern.

Alternatively, a heating element, such as a resistive heating element,may be used to transfer the transfer unit. The thermal transfer elementis selectively contacted with the heating element to cause thermaltransfer of a portion of the transfer layer according to a pattern. Inanother embodiment, the thermal transfer element may include a layerthat can convert an electrical current applied to the layer into heat.

Typically, the transfer layer is transferred to the receptor withouttransferring any of the other layers of the thermal transfer element,such as the optional interlayer and the LTHC layer. The presence of theoptional interlayer may eliminate or reduce the transfer of the LTHClayer to the receptor and/or reduce distortion in the transferredportion of the transfer layer. Preferably, under imaging conditions theadhesion of the interlayer to the LTHC layer is greater than theadhesion of the interlayer to the transfer layer. In some instances, areflective or an absorptive interlayer can be used to attenuate thelevel of imaging radiation transmitted through the interlayer and reduceany damage to the transferred portion of the transfer layer that mayresult from interaction of the transmitted radiation with the transferlayer and/or the receptor. This is particularly beneficial in reducingthermal damage which may occur when the receptor is highly absorptive ofthe imaging radiation.

Large thermal transfer elements can be used, including thermal transferelements that have length and width dimensions of a meter or more. Inoperation, a laser can be rastered or otherwise moved across the largethermal transfer element, the laser being selectively operated toilluminate portions of the thermal transfer element according to adesired pattern. Alternatively, the laser may be stationary and thethermal transfer element moved beneath the laser.

Thermal transfer donor substrates can be polymer films. One suitabletype of polymer film is a polyester film, for example, polyethyleneterephthalate or polyethylene naphthalate films. However, other filmswith sufficient optical properties (if light is used for heating andtransfer), including high transmission of light at a particularwavelength, as well as sufficient mechanical and thermal stability forthe particular application, can be used. The donor substrate, in atleast some instances, is flat so that uniform coatings can be formedthereon. The donor substrate is also typically selected from materialsthat remain stable despite heating of the LTHC layer. The typicalthickness of the donor substrate ranges from 0.025 to 0.15 mm,preferably 0.05 to 0.1 mm, although thicker or thinner donor substratesmay be used.

Typically, the materials used to form the donor substrate and the LTHClayer are selected to improve adhesion between the LTHC layer and thedonor substrate. An optional priming layer can be used to increaseuniformity during the coating of subsequent layers and also increase theinterlayer bonding strength between the LTHC layer and the donorsubstrate. One example of a suitable substrate with primer layer isavailable from Teijin Ltd. (Product No. HPE100, Osaka, Japan).

An optional interlayer may be disposed between the LTHC layer andtransfer layer in thermal transfer elements to minimize damage andcontamination of the transferred portion of the transfer layer and mayalso reduce distortion in the transferred portion of the transfer layer.The interlayer may also influence the adhesion of the transfer layer tothe rest of the thermal transfer element. Typically, the interlayer hashigh thermal resistance. Preferably, the interlayer does not distort orchemically decompose under the imaging conditions, particularly to anextent that renders the transferred image non-functional. The interlayertypically remains in contact with the LTHC layer during the transferprocess and is not substantially transferred with the transfer layer.

The interlayer may provide a number of benefits. The interlayer may be abarrier against the transfer of material to or from the light-to-heatconversion layer. It may also modulate the temperature attained in thetransfer layer so that thermally unstable materials can be transferred.The presence of an interlayer may also result in improved plastic memoryin the transferred material.

Thermal transfer elements can include an optional release layer. Theoptional release layer typically facilitates release of the transferlayer from the rest of the thermal transfer element (e.g., theinterlayer and/or the LTHC layer) upon heating of the thermal transferelement, for example, by a light-emitting source or a heating element.In at least some cases, the release layer provides some adhesion of thetransfer layer to the rest of the thermal transfer element prior toexposure to heat.

The release layer may be part of the transfer layer or a separate layer.All or a portion of the release layer may be transferred with thetransfer layer. Alternatively, most or substantially all of the releaselayer can remain with the donor substrate when the transfer layer istransferred. In some instances, for example with a release layer thatincludes a sublimable material, a portion of the release layer may bedissipated during the transfer process.

The transfer layers of thermal transfer elements of the presentinvention can include one or more layers for transfer to a receptor.These one or more layers may be formed using organic, inorganic,organometallic, and other materials. Although the transfer layer isdescribed and illustrated as having one or more discrete layers, it willbe appreciated that, at least in some instances where more than onelayer is used, there may be an interfacial region that includes at leasta portion of each layer. This may occur, for example, if there is mixingof the layers or diffusion of material between the layers before,during, or after transfer of the transfer layer. In other instances,individual layers may be completely or partially mixed before, during,or after transfer of the transfer layer. In any case, these structureswill be referred to as including more than one independent layer,particularly if different functions of the device are performed by thedifferent regions.

The transfer layer may include an adhesive layer disposed on an outersurface of the transfer layer to facilitate adhesion to the receptor.The adhesive layer may be an operational layer, for example, if theadhesive layer conducts charges between the receptor and the otherlayers of the transfer layer, or a non-operational layer, for example,if the adhesive layer only adheres the transfer layer to the receptor.The adhesive layer may be formed using, for example, thermoplasticpolymers, including conducting and non-conducting polymers, conductingand non-conducting filled polymers, and/or conducting and non-conductingdispersions.

The transfer layer may also include a release layer disposed on thesurface of the transfer layer that is in contact with the rest of thethermal transfer element. As described above, this release layer maypartially or completely transfer with the remainder of the transferlayer, or substantially all of the release layer may remain with thethermal transfer element, or the release layer may dissipate in whole orin part, upon transfer of the transfer layer. Suitable release layersare described above.

Although the transfer layer may be formed with discrete layers, it willbe understood that, in at least some embodiments, the transfer layer mayinclude layers that have multiple components and/or multiple uses in thedevice. It will also be understood that, at least in some embodiments,two or more discrete layers may be melted together during transfer orotherwise mixed or combined. In any case, these layers, although mixedor combined, will be referred to as individual layers.

The transfer of a one or more single or multicomponent transfer units toform at least a portion of an OEL (organic electroluminescent) deviceprovides a particularly illustrative, non-limiting example of theformation of an active device using a thermal transfer element. In atleast some instances, an OEL device includes a thin layer, or layers, ofone or more suitable organic materials sandwiched between a cathode andan anode. Electrons are injected into the organic layer(s) from thecathode and holes are injected into the organic layer(s) from the anode.As the injected charges migrate towards the oppositely chargedelectrodes, they may recombine to form electron-hole pairs which aretypically referred to as excitons. These excitons, or excited statespecies, may emit energy in the form of light as they decay back to aground state (see, for example, Tsutsui, MRS Bulletin, 22:39-45 (1997)).

Illustrative examples of OEL device constructions include molecularlydispersed polymer devices where charge carrying and/or emitting speciesare dispersed in a polymer matrix (see, for example, Kido, Trends inPolymer Science, 2:350-355 (1994)), conjugated polymer devices wherelayers of polymers such as polyphenylene vinylene act as the chargecarrying and emitting species (see, for example, Halls et al., ThinSolid Films, 276:13-20 (1996)), vapor deposited small moleculeheterostructure devices (see, for example, U.S. Pat. No. 5,061,569(VanSlyke et al.) and Chen et al., Macromolecular Symposia, 125:1-48(1997)), light emitting electrochemical cells (see, for example, Pei etal., J. Amer. Chem. Soc., 118:3922-3929 (1996)), and vertically stackedorganic light-emitting diodes capable of emitting light of multiplewavelengths (see, for example, U.S. Pat. No. 5,707,745 (Forrest et al.)and Shen et al., Science, 276:2009-2011 (1997)).

As used herein, the term “small molecule” refers to a non-polymericorganic, inorganic, or organometallic molecule, and the term “organicsmall molecule” refers to a non-polymer organic or organometallicmolecule. In OEL devices, small molecule materials can be used asemitter layers, as charge transport layers, as dopants in emitter layers(e.g., to control the emitted color) or charge transport layers, and thelike.

For many applications, such as display applications, it is preferredthat at least one of the cathode and anode be transparent to the lightemitted by the electroluminescent device. This depends on theorientation of the device (i.e, whether the anode or the cathode iscloser to the substrate) as well as the direction of light emission(i.e., through the substrate or away from the substrate).

The anode and cathode are typically formed using conducting materialssuch as metals, alloys, metallic compounds, metal oxides, conductiveceramics, conductive dispersions, and conductive polymers, including,for example, gold, platinum, palladium, aluminum, titanium, titaniumnitride, indium tin oxide (ITO), fluorine tin oxide (FTO), andpolyaniline. The anode and the cathode can be single layers ofconducting materials or they can include multiple layers. For example,an anode or a cathode may include a layer of aluminum and a layer ofgold, a layer of aluminum and a layer of lithium fluoride, or a metallayer and a conductive organic layer. It may be particularly useful toprovide a two-layer cathode (or anode) consisting of a conductiveorganic layer (e.g., 0.1 to 5 micrometers thick) and a thin metal ormetal compound layer (e.g., 100 to 1000 Angstroms). Such a bilayerelectrode construction may be more resistant to moisture or oxygen thatcan damage underlying moisture- or oxygen-sensitive layers in a device(e.g., organic light emitting layers). Such damage can occur when thereare pinholes in the thin metal layer, which can be covered and sealed bythe conductive organic layer. Damage and/or device failure can be causedby cracking or fracturing of the thin metal layer. Addition of aconductive organic layer can make the metal layer more resistant tofracture, or can act as a diffusion barrier against corrosive substancesand as a conductive bridge when fracturing occurs.

The hole transport layer facilitates the injection of holes into thedevice and their migration towards the cathode. The hole transport layercan further act as a barrier for the passage of electrons to the anode.The hole transport layer can include, for example, a diamine derivative,such as N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (also known asTPD) or other hole conductive materials such asN,N′-bis(3-naphthalen-2-yl)-N,N′-bis(phenyl)benzidine (NBP). In general,the hole transport layer can include organic small molecule materials,conductive polymers, a polymer matrix doped with an organic smallmolecule, and other suitable organic or inorganic conductive orsemiconductive materials.

The electron transport layer facilitates the injection of electrons andtheir migration towards the anode. The electron transport layer canfurther act as a barrier for the passage of holes to the cathode.

The emitter layer is often formed from a metal chelate compound, suchas, for example, tris(8-hydroxyquinoline) aluminum (ALQ). Emitter layerscan also include light emitting polymers such aspoly(phenylenevinylene)s (PPVs), poly-para-phenylenes (PPPs), andpolyfluorenes (PFs); organic small molecule materials, of which ALQ isan example; polymers doped with organic small molecules; and othersuitable materials.

Optionally, the electron transport layer can be doped with a fluorescentor phosporescent dye as described herein. Doped electron transportlayers are sometimes referred to herein as electron transport/emitterlayers. In preferred embodiments, the electron transport layer is dopedwith a blue fluorescent dye.

For embodiments that include an electron transport/emitter layer, theinterface between the hole transport layer and electrontransport/emitter layer forms a barrier for the passage of holes andelectrons and thereby creates a hole/electron recombination zone andprovides an efficient organic electroluminescent device. When theemitter material is ALQ, the OEL device emits blue-green light. Theemission of light of different colors may be achieved by the use ofdifferent emitters and dopants in the electron transport/emitter layer(see, for example, Chen et al., Macromolecular Symposia, 125:1-48(1997)).

For embodiments that include an electron transport/emitter layer and asecond emitter layer, the electron transport/emitter layer can beprepared to function solely as an electron transport layer so thatrecombination and emission is confined to the second emitter layer.Preferably, this construction is capable of providing an efficientorganic electroluminescent device.

Other OEL multilayer device constructions may include, for example, ahole transport layer that is also an emitter layer. Alternatively, thehole transport layer and the electron transport/emitter layer could becombined into one layer. Furthermore, a separate emitter layer could beinterposed between a hole transport layer and an electron transportlayer.

Patterning OEL materials and layers to form OEL devices provides aparticularly suited example to illustrate some difficulties withconventional patterning techniques and how these difficulties can beovercome according to the present invention. With conventionalpatterning techniques, there may be some materials or layers that cannotbe used due to susceptibility to attack, penetration, or dissolutionfrom exposure to solvents or etchants used to coat or pattern otherlayers on the display substrate. Thus, there may be device and/ordisplay constructions that cannot be made by conventional techniquesbecause a solvent-coated layer would be coated on a solvent-susceptiblelayer, or because an etchant would be used to pattern layers on otherlayers that are susceptible to the etchant. For example, in forming anOEL device that includes an anode on a substrate, a small molecule holetransport layer on the anode, a light emitting polymer emitter on thehole transport layer, and a cathode on the emitter layer, the solventused to coat the light emitting polymer may damage the hole transportlayer under conventional processing techniques. The same limitations mayhold for conventional patterning of adjacent OEL devices, one of whichmay contain a light emitting polymer emitter layer and the other ofwhich may contain an organic small molecule emitter layer. Theselimitations can be overcome using thermal patterning methods of thepresent invention. Overcoming these limitations allows a wider range ofpossible device constructions and materials alternatives, and these inturn may be used to achieve OEL devices and displays that exhibitcharacteristics such as brightness, lifetime, color purity, efficiency,etc., that might not otherwise be achieved. Thus, the present inventionprovides new OEL device and display constructions as well as newpatterning methods.

As discussed, OEL devices can be formed by selective thermal transferfrom one or more donor elements. Multiple devices can also betransferred onto a receptor to form a pixilated display. Alternatively,the red, green, and blue thermal transfer elements could be transferredon top of one another to create a multi-color stacked OLED device of thetype disclosed in U.S. Pat. No. 5,707,745 (Forrest et al.).

Still another method for forming multi-color pixilated OEL displays isto pattern red, green, and blue emitters (for example) from threeseparate donors, and then, in a separate step, to pattern all thecathodes (and, optionally, electron transport layers) from a singledonor element. In this way, each OEL device is patterned by at least twothermal transfers, the first of which patterns the emitter portion (and,optionally, an adhesive layer, a buffer layer, anode, hole injectionlayer, hole transport layer, electron blocking layer, and the like), andthe second of which patterns the cathode portion (and, optionally, anelectron injecting layer, electron transport layer, hole blocking layer,and the like).

One advantage of splitting the device layers between two or more donorelements (e.g., an emitter donor and a cathode donor) is that the samedonor elements can be used to pattern the emitter portion of OEL devicesfor either passive matrix or active matrix display constructions.Generally, active matrix displays include a common cathode that isdeposited over all the devices. For this construction, thermal transferof an emitter stack that includes a cathode may not be necessary, andhaving a cathode-less transfer stack may be desirable. For passivematrix displays, cathode-less donors can be used to transfer each of theemitter portions (a different donor for each color, if multi-color isdesired), followed by patterning of the cathodes for each device fromthe same, separate donor element. Alternately, the cathode of a passivematrix display can be patterned using the method described by Y.-H Taket al., Synthetic Metals, 138:497 (2003), in which a common cathode isapplied to the substrate and subsequently separated by a laser ablationprocess. Thus, various emitter donors can be used for various displayconstructions.

Another advantage of the present invention is that OEL devices, forexample, can be transferred and patterned according to the describedmethods to form adjacent devices having different, and otherwiseincompatible, types of emitter materials. For example, red-emittingorganic small molecule devices (e.g., that use an active vapor-depositedsmall molecule layer) can be patterned on the same receptor asblue-emitting light emitting polymer devices (e.g., that use an activesolution-coated light emitting polymer layer). This allows flexibilityto choose light-emitting materials (and other device layer materials)based on functionality (e.g., brightness, efficiency, lifetime,conductivity, physical properties after patterning (e.g., flexibility,etc.)) rather than on compatibility with the particular coating and/orpatterning techniques used for the other materials in the same oradjacent devices. The ability to choose different types of emittermaterials for different color devices in an OEL display can offergreater flexibility in choosing complementary device characteristics.The ability to use different types of emitters can also become importantwhen the preferred emitter material for one OEL device is incompatiblewith the preferred emitter material for another OEL device.

The substrate may be any item suitable for a particular applicationincluding, but not limited to, transparent films, display blackmatrices, passive and active portions of electronic displays (e.g.,electrodes, thin film transistors, organic transistors, etc.), metals,semiconductors, glass, various papers, and plastics. Non-limitingexamples of substrates which can be used in the present inventioninclude anodized aluminum and other metals, plastic films (e.g.,polyethylene terephthalate, polypropylene), indium tin oxide coatedplastic films, glass, indium tin oxide coated glass, flexible circuitry,circuit boards, silicon or other semiconductors, and a variety ofdifferent types of paper (e.g., filled or unfilled, calendered, orcoated). For OEL displays, the type of substrate used often depends onwhether the display is a top emitting display (emitter layer or layerspositioned between the viewer and the substrate), a bottom emittingdisplay (substrate positioned between the viewer and the emitter layeror layers), or both a top and bottom emitting display. For a topemission display, the substrate need not be transparent. For a bottomemission display, a transparent substrate is typically desired.

When a substrate is used as a receptor (e.g., as a receptor for athermally transferred layer), various layers (e.g., an adhesive layer)may be coated onto the substrate to facilitate transfer of the transferlayer to the receptor. Other layers may be coated on the substrate toform a portion of a multilayer device. For example, an OEL or otherelectronic device may be formed using a substrate having a metal and/orconductive organic anode or cathode formed on the substrate prior totransfer of the transfer layer from the thermal transfer element. Theanode or cathode may be formed, for example, by depositng one or moreconductive layers on the substrate and patterning of the layer(s) intoone or more anodes or cathodes using any suitable method, for example,photolithographic techniques or the thermal transfer techniques taughtherein.

A particularly useful substrate for patterning multilayer devices is onethat has a common electrode or a pattern of electrodes along with apattern of insulating barriers on top of at least a portion of theelectrode(s). The insulating barriers can be provided in a pattern thatcorresponds to the intended position of the edges of the multilayerdevices to help prevent electrical shorts between the receptorelectrode(s) and the opposing electrode transferred along with or on topof a multilayer stack. This is especially useful in passive matrixdisplays. Also, in active matrix display constructions, the insulatingbarriers can help isolate the transistors of the active matrix from thecommon electrode, which is generally provided. This can help preventleakage currents and parasitic capacitance which can reduce deviceefficiencies.

Electroluminescent (EL) devices emit light toward a viewer position andmay to be characterized as “bottom anode” or “top anode.” The terms“bottom anode” and “top anode” indicate the relative positions of theanode, the substrate, and the cathode. In a “bottom anode” device, theanode is positioned between the substrate and the cathode. In a “topanode” device, the cathode is positioned between the anode and thesubstrate. In some embodiments described herein, the substrate may be areceptor or part of a receptor (e.g., a receptor for thermallytransferred materials).

Bottom anode and top anode devices may be further characterized as“bottom emitting” or “top emitting.” The terms “bottom emitting” and“top emitting” indicate the relative positions of the substrate, theemitter layer or layers, and the viewer. The viewer position generallyindicates the intended destination for the emitted light whether the“viewer” is a human observer, a screen, an optical component, anelectronic device, or the like. In bottom emitting EL devices, atransparent or semitransparent substrate is positioned between theemitter layer or layers and the viewer. In the inverted, or topemitting, configuration, the emitter layer or layers are positionedbetween the substrate and the viewer.

In general, device constructions disclosed herein are illustrated in asimplified manner to exemplify preferred embodiments of the presentinvention. The inclusion of an additional layer or layers that would bedesirable in the construction of specific devices would be obvious toone of skill in the art. Thus, the device constructions illustratedherein are not intended to be limited solely to the specific layersdescribed herein, but should be broadly interpreted as includingadditional layers as desired.

Turning now to the drawings, FIGS. 1A to 1C illustrate the assembly ofan electroluminescent device according to the invention, and inparticular a “bottom anode” configuration.

One or more patterned emitter layers 130 including a first emitter(e.g., red, green, or blue light emitting) are disposed on receptor 120,which may be an anode or a layer attached to an anode. In someembodiments, patterned emitter layers 130 include a non-volatilecomponent, which may be the same as or different than the first emitter.In some embodiments, patterned emitter layers 130 are disposed onreceptor 120 by selectively thermally transferring a portion of atransfer layer including a first emitter to receptor 120 to formpatterned emitter layers 130.

Optionally, referring to FIG. 1B, one or more additional patternedemitter layers 140 including additional emitters may be disposed onreceptor 120. In some embodiments, patterned emitter layers 140 mayinclude non-volatile components, which may be the same as or differentthan the additional emitters. In some embodiments, additional patternedemitter layers 140 are disposed on receptor 120 by selectively thermallytransferring portions of one or more additional transfer layersincluding additional emitters. Preferably, the additional emitters emitdifferent colors of light than the first emitter.

Referring to FIG. 1C, a layer including a second emitter is thendisposed on the patterned emitter layers to form non-patterned emitterlayer 150 (e.g., red, green or blue light emitting). Preferably, thesecond emitter layer 150 emits a different color of light than the firstemitter layer 130 and any additional emitter layers 140.

In some embodiments, receptor 120 is solvent-susceptible. Receptor 120may also be, for example, a hole transport layer, a hole injectionlayer, an electron blocking layer, a dielectric layer, a passivationlayer, or a combination thereof. Receptor 120 may be attached, forexample, to anode 110, which is preferably patterned. Additional layersmay be disposed between receptor 120 and anode 110. For example, ifreceptor 120 is a hole transport layer, hole injection layer 114 may bedisposed between receptor 120 and anode 110. Further, anode 110 may beattached to substrate 105.

Non-patterned emitter layer 150 may further be, for example, an electrontransport layer that may optionally be doped (e.g., with a fluorescentor phosphorescent dye), a hole blocking layer that may optionally bedoped (e.g., with a fluorescent or phosphorescent dye), or a combinationthereof. Cathode 160 may be disposed on non-patterned emitter layer 150.

For embodiments wherein the electroluminescent device is a bottomemitting device, anode 110 and substrate 105 are transparent, andcathode 160 is preferably opaque.

For embodiments wherein the electroluminescent device is a top emittingdevice, cathode 160 is transparent, and anode 110 and/or substrate 105are preferably opaque.

A configuration in which substrate 105, anode 110, and cathode 160 areall transparent is considered to be both top and bottom emitting.

FIGS. 2A to 2C illustrate the assembly of an electroluminescent deviceaccording to the invention and in particular a “top anode”configuration.

A non-patterned layer 220 including a first emitter (e.g., red, green,or blue light emitting) is provided. One or more patterned emitterlayers 230 including a second emitter are disposed on non-patternedemitter layer 220. In some embodiments, patterned emitter layers 230include a non-volatile component, which may be the same or differentthan the second emitter. In some embodiments, patterned emitter layers230 are disposed on non-patterned emitter layer 220 by selectivelythermally transferring a portion of a transfer layer including a secondemitter to non-patterned emitter layer 220 to form patterned emitterlayers 230.

Optionally, referring to FIG. 2B, one or more additional patternedemitter layers 240 including additional emitters may be disposed onnon-patterned emitter layer 220. In some embodiments, patterned emitterlayers 240 may include non-volatile components, which may be the same asor different than the additional emitters. In some embodiments,additional patterned emitter layers 240 are disposed on non-patternedemitter layer 220 by selectively thermally transferring portions of oneor more additional transfer layers including additional emitters.Preferably, the additional emitters emit different colors of light thanthe first and second emitters.

Optionally, referring to FIG. 2C, anode 250 may be disposed on patternedemitter layers 230 and, if present, additional patterned emitter layers240. Additional layers may be disposed between anode 250 and patternedemitter layers 230 and, if present, patterned emitter layers 240. Forexample, hole transport layer, hole injection layer, or electronblocking layer 244 may be disposed between anode 250 and patternedemitter layers 230 and, if present emitter layers, 240.

In some embodiments, non-patterned emitter layer 220 issolvent-susceptible. Non-patterned emitter layer may further be, forexample, an electron transport layer that may optionally be doped (e.g.,with a fluorescent or phosphorescent dye), a hole blocking layer thatmay optionally be doped (e.g., with a fluorescent or phosphorescentdye), an electron injecting layer that may optionally be doped (e.g.,with a fluorescent or phosphorescent dye), or a combination thereof.Non-patterned emitter layer 220 may be attached, for example, to cathode210, which is preferably patterned. Further, cathode 210 may beattached, for example, to substrate 205.

For embodiments wherein the electroluminescent device is a bottomemitting device, cathode 210 is transparent, substrate 205, if present,is transparent, and anode 250 is preferably opaque.

For embodiments wherein the electroluminescent device is a top emittingdevice, anode 250 is transparent, and cathode 210 and/or substrate 205are preferably opaque.

A configuration in which substrate 205, anode 250, and cathode 210 areall transparent, is considered to be both top and bottom emitting.

The devices schematically illustrated in FIGS. 1A to 1C and 2A to 2C arepreferably operable to emit light by providing a signal to the anode andthe cathode. Preferably the signal is operable to address an emitter,following which the emitter emits light. In general, arrays of pixels orsub-pixels may be addressed using active or passive addressing schemesas defined herein above. Both full color display devices and tunablelighting devices are possible within the scope of the invention. A fullcolor display device generally employs three emitters, each emittinglight of a different color such as red, green and blue light. A tunablelighting device generally uses two emitters, each emitting light of adifferent color. The device may be operated by providing current to eachof the subpixels within a pixel. A change in the ratio of currents tothe subpixels will affect both the color and the brightness of the lightemitted from the pixel.

EXAMPLES

The present invention is illustrated by and will be more fullyappreciated with reference to the following non-limiting examples. Theparticular examples, materials, amounts and procedures are to beinterpreted broadly in accordance with the scope and spirit of theinvention as set forth herein.

Unless otherwise specified, all parts are parts by weight, and allratios and percentages are by weight. For simplicity, variousabbreviations are used in the examples and have the meaning given and/ordescribe materials that are commercially available as noted in thefollowing table. Abbreviation Description/Commercial Source PEDOT Amixture of water and 3,4-polyethylenedioxythiophene-polystyrenesulfonate(cationic) available from H. C. Starck, Newton, MAas PEDOT VP AI 4083 EL111T A material for forming a layer of anelectroluminescent device available from Hodogaya Chemical Co., Ltd.,Kawasaki, Japan as EL111T 2-mTNATA4,4′,4″-tris(N-(2-naphthyl)-N-(3-methylphenyl)-amino)- triphenylamineavailable from Bando Chemical Industries, Kobe, Japan as 2-MTNATA ST1693.S 2,7-bis-(N-phenyl-N-(4′-N,N-diphenylamino-biphenyl-4-yl))-9,9-dimethyl-fluorene, sublimed, available from Syntec GmbH,Wolfen, Germany as ST 1693.S ST 755.S1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)- cyclohexane, sublimed,available from Syntec GmbH, Wolfen, Germany as ST 755.S LEP Covion SuperYellow, PDY 132, a yellow emitter available from Covion Semiconductors,Frankfurt, Germany PS Polystyrene standard, typical M_(w) = 2500,available as product number 32,771-9 from Aldrich Chemical Company,Milwaukee, WI PVK Poly-N-vinyl carbazole, available as product numberP2236-VK from Polymer Source Inc., Dorval, Canada MTDATA4,4′,4″-tris(N-3-methylphenyl-N- phenylamino)triphenylamine, sublimed,available from H. W. Sands Corp., Jupiter, FL as product number OSA3939PBD 2-(4-biphenylyl)-5-(4-tertbutylphenyl)-1,3,4-oxadiazole), availablefrom Dojindo Laboratories, Kumamoto, Japan EL028T A material for forminga layer of an electroluminescent device available from Hodogaya ChemicalCo., Ltd., Kawasaki, Japan as EL028T TPOB A material prepared accordingto the procedure described in Noda et al., J. Mater. Chem., 9: 2177-2181(1999) Spiro-CF₃-PBD A material for forming a layer of anelectroluminescent device available from Covion Semiconductors,Frankfurt, Germany as Spiro-CF₃-PBD Ir(ppy)₃-S-C-1 A green emitteravailable from Covion Semiconductors, Frankfurt, Germany Ir(ppy)₂(tmhd)A green emitter prepared according to the procedure described inLamansky et al., J. Am. Chem. Soc., 123: 4304-4312 (2001) Ir(btp)₂(tmhd)A red emitter prepared according to the procedure described in Lamanskyet al., J. Am. Chem. Soc., 123: 4304-4312 (2001) BAlqBis-(2-methyl-8-quinolato)-4-(phenyl-phenolato)- aluminum-(III),sublimed, available from Eastman Kodak Company, Rochester, NY Peryleneblue dye Available from Aldrich Chemical Company, Milwaukee, WI LiFLithium fluoride, 99.85%, available as product number 36359 from AlfaAesar, Ward Hill, MA Aluminum Puratronic aluminum shots, 99.999%,available from Alfa Aesar, Ward Hill, MA FC Surfactant A fluorochemicalsurfactant prepared according to Example 5 of U.S. Pat. No. 3,787,351Ebecryl 629 An epoxynovolac acrylate available from UCB Radcure Inc., N.Augusta, SC as Ebecryl 629 Elvacite 2669 An acrylic resin available fromICI Acrylics Inc., Memphis, TN as Elvacite 2669 Irgacure 3692-benzyl-2-(dimethylamino)-1-(4-(morpholinyl)phenyl) butanone, availablefrom Ciba Specialty Chemicals Corporation, Tarrytown, NY as Irgacure 369Irgacure 184 1-hydroxycyclohexyl phenyl ketone, available from CibaSpecialty Chemicals Corporation, Tarrytown, NY as Irgacure 184 M7Q filmA 0.076 mm thick polyethylene terephthalate film available from Teijin,Osaka, Japan as M7Q UV Ultraviolet nm Nanometer m Meter min Minute SR351HP Trimethylolpropane triacrylate ester, available from Sartomer,Exton, PA as SR 351HP LITI Laser-induced thermal imaging ITO Indium tinoxide Block pixel ITO glass Glass substrate having a region of ITOmeasuring 50 mm × 50 mm × 0.7 mm and a resistance of <20 Ohm/sq,available from Delta Technologies, Stillwater, MN Striped pixel ITOglass Glass substrate having a region of ITO measuring 50 mm × 50 mm ×0.7 mm, said region comprising a pattern of adjacent, parallel 75micrometers wide stripes of ITO with a pitch of 165 micrometers and aresistance of <20 Ohm/sq, available from Delta Technologies, Stillwater,MN LTHC Light-to-heat conversion Raven 760 Ultra Carbon black pigment,available from Columbian Chemical Co., Atlanta, GA as Raven 760 UltraButvar B-98 Polyvinyl butyrol resin, available from Solutia, Inc., St.Louis, MO as Butvar B-98 Joncryl 67 Acrylic resin available from S.C.Johnson & Sons, Racine, WI as Joncryl 67 Disperbyk 161 A dispersantavailable from Byk-Chemie, USA, Wallingford, CT as Disperbyk 161 Wt. %Weight percent Puradisc filter A 0.45 micrometer polypropylene filteravailable from Whatman Inc., Clifton, NJ under the tradename Puradisc

Materials not identified in the foregoing table were obtained fromAldrich Chemical Company, Milwaukee, Wis., unless noted otherwise.

General Preparation of Donor Film

A donor film was used in each example and was prepared as described inthis general preparation. A LTHC solution was prepared by mixing 3.55parts Raven 760 Ultra, 0.63 parts Butvar B-98, 1.90 parts Joncryl 67,0.32 parts Disperbyk 161, 0.09 parts FC Surfactant, 12.09 parts Ebecryl629, 8.06 parts Elvacite 2669, 0.82 parts Irgacure 369, 0.12 partsIrgacure 184, 45.31 parts 2-butanone, and 27.19 parts 1,2-propanediolmonomethyl ether acetate. This solution was coated onto M7Q film using aYasui Seiki Lab Coater, Model CAG-150, with a microgravure roll having110 helical cells per inch. The LTHC coating was in-line dried at 80° C.and cured under UV radiation supplied by a Fusion UV Systems Inc. 600Watt D bulb at 100% energy output (UVA 320 to 390 nm) with an exposurespeed of 6.1 m/min.

An interlayer solution was made by mixing 14.85 parts SR 351 HP, 0.93parts Butvar B-98, 2.78 parts Joncryl 67, 1.25 parts Irgacure 369, 0.19parts Irgacure 184, 48 parts 2-butanone, and 32 parts1-methoxy-2-propanol. This solution was coated onto the cured LTHC layerby a rotogravure method using a Yasui Seiki lab coater, Model CAG-150,with a microgravure roll having 180 helical cells per lineal inch. Thiscoating was in-line dried at 60° C. and cured under UV radiationsupplied by passing the coating under a Fusion UV Systems Inc. 600 WattD bulb at 60% energy output (UVA 320 to 390 nm) at 6.1 m/min.

Example 1

Example 1 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer, and a layer comprising a second emitter isdisposed on the patterned emitter layer to provide a non-patternedemitter layer.

Preparation of Receptor

PEDOT was filtered twice using a Puradisc filter, and spin-coated onto ablock pixel ITO glass substrate to yield a layer having a dry thicknessof 40 nm. The coated glass substrate was baked for 5 minutes at 200° C.under a nitrogen atmosphere. Using methanol, the coated layer wasselectively removed from portions of the ITO region to provide contactareas for connecting the receptor to a power supply.

Preparation of Donor

LEP (a yellow emitter) and PS were combined in a 1:3 weight ratio,diluted with HPLC grade toluene to 1.58 wt. %, heated and stirred at 70°C., filtered once using a Puradisc filter, and spin-coated onto a donorfilm prepared as described in the General Preparation to yield atransfer layer having a dry thickness of 90 nm.

Selective Thermal Transfer of Patterned Emitter Layer

The transfer layer from the donor was imaged onto the receptor by LITIto yield a patterned emitter layer. Two lasers were used at a power of16 watts in a unidirectional scan with a triangle dither pattern andfrequency of 400 KHz. The requested line width was 100 micrometers witha pitch of 225 micrometers, and the dose was 0.650 J/cm².

Deposition of Non-Patterned Emitter Layer

A 500 Å thick layer of BAlq doped with approximately 0.5-1% by weightperylene blue dye was deposited via a standard vacuum depositiontechnique onto the patterned emitter layer under a vacuum ofapproximately 10⁻⁵ torr and using a shadow mask that prevented thematerial from being deposited on the ITO contact area for connecting toa power supply.

Deposition of Cathode

A two layer cathode consisting of a 10 Å thick film of LiF followed by a2000 Å thick film of aluminum were sequentially deposited on thenon-patterned emitter layer. Deposition was carried out under a vacuumof approximately 10⁻⁶ torr and using a second shadow mask that allowedfor contact between the cathode and the ITO contact area on thereceptor.

Preparation of Control Device Corresponding to Example 1

A control device corresponding to the device of Example 1 was preparedto demonstrate that the yellow emission color from the patterned emitterlayer was unaffected by the presence of the perylene blue dye in thenon-patterned emitter layer.

The control device comprised a receptor like that employed in Example 1.LEP (a yellow emitter) and PS were combined in a 1:3 weight ratio,diluted with HPLC grade toluene to 1.58 wt. %, heated and stirred at 70°C., filtered once through a Puradisc filter, and immediately spin coatedon to the receptor to a dry thickness of 90 nm. This provided anon-patterned emitter layer that corresponded in composition to thepatterned emitter layer in Example 1. The coated layer was selectivelyremoved from portions of the ITO region to provide contact areas forconnecting the receptor to a power supply.

A layer containing perylene blue dye was prepared and deposited on thenon-patterned emitter layer. More specifically, a 500 Å thick layer ofBAlq doped with approximately 0.5-1% by weight perylene blue dye wasdeposited via a standard vacuum deposition technique onto thenon-patterned emitter layer under a vacuum of approximately 10⁻⁵ torr. Ashadow mask was used to prevent the material from being deposited on theITO contact area for connecting to a power supply.

A cathode was deposited on the layer containing perylene blue dye byfollowing the procedure used for the cathode in Example 1.

Electroluminescence Spectra

Electroluminescence spectra for Example 1 and its control device wereobtained by driving the devices with a Keithley Source Meter 2400(Keithley Instruments, Cleveland, Ohio) and recording the output at fourdifferent device current densities (10, 20, 30 and 40 mA/cm²) with anOcean Optics Fiber Optic Fluorescent Spectrometer (Ocean Optics Inc.,Dunedin, Fla.).

Example 1 showed a pattern of yellow stripes contributed by thepatterned emitter layer and, between the yellow stripes, blue stripescontributed by the non-patterned emitter layer. The control device,however, showed only a yellow area contributed by the non-patternedemitter layer and no blue area. Thus, in both devices, the layercontaining perylene blue dye substantively provided only anelectron-transport function where it was deposited on the layercontaining the yellow emitter (i.e., the patterned emitter layer inExample 1, and the non-patterned emitter layer in the control device)with no observable shift of the exciton recombination zone to the layercontaining the perylene blue dye. These devices also demonstrate theindependence of spectral characteristics and CIE color coordinates ofdriving current.

Example 2

Example 2 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer, and a layer comprising a second emitter isdisposed on the patterned emitter layer to provide a non-patternedemitter layer.

Preparation of Receptor

A receptor was prepared following the procedure used in Example 1.

Preparation of Donor

PVK-4, MTDATA, PBD, and Ir(btp)₂(tmhd) (a red emitter) were combined ina 42:28:27:3 weight ratio and then diluted with HPLC grade toluene to1.97% by weight. The resulting solution was filtered twice through aPuradisc filter and spin-coated onto a donor film prepared as describedin the General Preparation to yield a transfer layer having a drythickness of 55 nm.

Selective Thermal Transfer of Patterned Emitter Layer

The transfer layer from the donor was imaged onto the receptor by LITIto yield a patterned emitter layer. One laser was used at a power of 4watts in a unidirectional scan with a triangle dither pattern andfrequency of 400 KHz. The requested line width was 100 micrometers witha pitch of 225 micrometers and the dose was 0.875 J/cm².

Deposition of Non-Patterned Emitter Layer and Deposition of Cathode

A non-patterned emitter layer containing perylene blue dye and atwo-layer cathode were then deposited on the patterned emitter layerfollowing the procedure described in conjunction with Example 1 for thedeposition of these layers.

Preparation of Control Device Corresponding to Example 2

A control device corresponding to the device of Example 2 was preparedto demonstrate that the red emission color from the patterned emitterlayer was unaffected by the presence of the perylene blue dye in thenon-patterned emitter layer.

The control device comprised a receptor like that employed in Example 2.PVK-4, MTDATA, PBD, and Ir(btp)₂(tmhd) (red emitter) were combined in a42:28:27:3 weight ratio and then diluted with HPLC grade toluene to1.97% by weight. The resulting solution was filtered twice through aPuradisc filter and spin-coated on to the receptor to a dry thickness of50 nm to provide a non-patterned emitter layer that corresponded incomposition to the patterned emitter layer in Example 2. The coatedlayer was selectively removed from portions of the ITO region to providecontact areas for connecting the receptor to a power supply.

A layer containing perylene blue dye was prepared and deposited on thenon-patterned emitter layer. More specifically, a 500 Å thick layer ofBAlq doped with approximately 0.5-1% by weight perylene blue dye wasdeposited via a standard vacuum deposition technique onto thenon-patterned emitter layer under a vacuum of approximately 10⁻⁵ torr. Ashadow mask was used to prevent the material from being deposited on theITO contact area for connecting to a power supply.

A cathode was applied to the layer containing perylene blue dye byfollowing the procedure used for the cathode in Example 2.

Electroluminescence Spectra

Electroluminescence spectra for Example 2 and its control device wereobserved by applying electrical power to the devices with an AgilentE3612 DC power supply (Agilent Technologies, Palo Alto, Calif.) andmicroscopically examining the electroluminescence with a Nikon EclipseTE300 inverted optical microscope (Nikon Corporation, Tokyo, Japan).

Example 2 showed a pattern of red stripes contributed by the patternedemitter layer and, between the red stripes, blue stripes contributed bythe non-patterned emitter layer. The control device, however, showedonly a red area contributed by the non-patterned emitter layer and noblue area. Thus, in both devices, the layer containing perylene blue dyesubstantively provided only an electron-transport function where it wasdeposited on the layer containing the red emitter (i.e., the patternedemitter layer in Example 2, and the non-patterned emitter layer in thecontrol device) with no observable shift of the exciton recombinationzone to the layer containing the perylene blue dye.

Example 3

Example 3 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer, and a layer comprising a second emitter isdisposed on the patterned emitter layer to provide a non-patternedemitter layer. Example 3 was prepared by following the procedure ofExample 2 except that the Ir(btp)₂(tmhd) red emitter was replaced byIr(ppy)₂(tmhd), a green emitter.

Preparation of Control Device Corresponding to Example 3

A control device corresponding to the device of Example 3 was preparedto demonstrate that the green emission color from the patterned emitterlayer was unaffected by the presence of the perylene blue dye in thenon-patterned emitter layer. The control device for Example 3 wasprepared by following the procedure used in conjunction with the controldevice for Example 2, except that the Ir(btp)₂(tmhd) red emitter wasreplaced by Ir(ppy)₂(tmhd), a green emitter.

Electroluminescence Spectra

Electroluminescence spectra for Example 3 and its control device wereobserved using the procedure described in conjunction with Example 2.

Example 3 showed a pattern of green stripes contributed by the patternedemitter layer and, between the green stripes, blue stripes contributedby the non-patterned emitter layer. The control device, however, showedonly a green area contributed by the non-patterned emitter layer and noblue area. Thus, in both devices, the layer containing perylene blue dyesubstantively provided only an electron-transport function where it wasdeposited on the layer containing the green emitter (i.e., the patternedemitter layer in Example 3, and the non-patterned emitter layer in thecontrol device) with no observable shift of the exciton recombinationzone to the layer containing the perylene blue dye.

Example 4

Example 4 illustrates a method of making an electroluminescent deviceaccording to the invention in which transfer layers comprising a firstemitter and a second emitter are selectively thermally transferred to areceptor to form a patterned emitter layer, and a layer comprising athird emitter is disposed on the patterned emitter layer to provide anon-patterned emitter layer. The first emitter was provided by the redemitter of Example 2, and the second emitter was provided by the greenemitter of Example 3.

A receptor was prepared by following the procedure described inconjunction with Example I and separate donors, each containing atransfer layer, were prepared according to Example 2 (red emitter) andExample 3 (green emitter). The transfer layer containing the red emitterwas imaged onto the receptor by LITI using the laser arrangementdescribed in Example 2, except with a pitch of 300 micrometers. Thetransfer layer containing the green emitter was imaged onto the samereceptor, also by LITI and again using the laser arrangement describedin Example 2, except with a pitch of 300 micrometers. The origin for thetransfer layer containing the green emitter was shifted +100 micrometersrelative to the origin for the transfer layer containing the redemitter.

A non-patterned emitter layer containing perylene blue dye and atwo-layer cathode were then deposited on the patterned emitter layercontaining the first (red) and second (green) emitters using theprocedure described in conjunction with Example 1 for the deposition ofthese layers.

Electroluminescence Spectra

The electroluminescence spectrum for Example 4 was observed using theprocedure described in conjunction with Example 2 and showed a patternof alternating red, green and blue stripes, the red and green emissionpatterns corresponding to the areas patterned by selective thermaltransfer via LITI.

Example 5

Example 5 illustrates a method of making an electroluminescent deviceaccording to the invention in which transfer layers comprising a firstemitter and a second emitter are selectively thermally transferred to areceptor to form a patterned emitter layer on a solvent-susceptiblelayer, and a layer comprising a third emitter is disposed on thepatterned emitter layer to provide a non-patterned emitter layer.

Preparation of Receptor

A solution of EL111T was made at 5.0% by weight in HPLC grade tolueneand allowed to stir for 20 minutes at 70° C. on a hotplate. The solutionwas then filtered through a Puradisc filter and spin-coated onto stripedpixel ITO glass to yield a solvent-susceptible layer having a drythickness of 160 nm. Using toluene, the coated layer was selectivelyremoved from portions of the ITO region to provide contact areas forconnecting the receptor to a power supply.

Preparation of Donor

To prepare a first donor corresponding to the first emitter, EL028T,Spiro-CF₃-PBD, and Ir(btp)₂(tmhd), a red emitter, were combined in a45:45:10 weight ratio, diluted with chlorobenzene to 1.35% by weight,and allowed to stir for 20 minutes at 70° C. on a hotplate. Theresulting solution was filtered once through a Puradisc filter andspin-coated onto a donor film prepared as described in the GeneralPreparation to yield a transfer layer having a dry thickness of 50 nm. Asecond donor corresponding to the second emitter was prepared in thesame manner but substituting a green emitter, Ir(ppy)₃-S-C-1, for thered emitter.

Selective Thermal Transfer of Patterned Emitter Layers

The transfer layer from the first donor was imaged onto the receptor byLITI to yield a patterned emitter layer. One laser was used at a powerof 4 watts in a unidirectional scan with a triangle dither pattern andfrequency of 400 KHz. The requested line width was 110 micrometers witha pitch of 495 micrometers and the dose was 0.85 J/cm². The transferlayer from the second donor was then imaged onto the same receptor byLITI and using the same laser arrangement to provide a patterned emitterlayer comprising first (red) and second (green) emitters. The origin forthe transfer layer containing the green emitter was shifted +165micrometers relative to the origin for the transfer layer containing thered emitter.

Deposition of Non-Patterned Emitter Layer and Deposition of Cathode

A non-patterned emitter layer containing perylene blue dye and atwo-layer cathode were then deposited on the patterned emitter layercomprising the first (red) and second (green) emitters following theprocedure described in conjunction with Example I for the deposition ofthese layers.

Electroluminescence Spectra

The electroluminescence spectrum for Example 5 was observed using theprocedure described in conjunction with Example 2 and showed a patternof alternating red, green and blue stripes, the red and green emissionpatterns corresponding to the areas patterned by the selective thermaltransfer via LITI.

Example 6

Example 6 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer on a solvent-susceptible layer, and a layercomprising a second emitter is disposed on the patterned emitter layerto provide a non-patterned emitter layer.

Preparation of Receptor

A solution of 2-mTNATA was made at 6.0% by weight in HPLC grade toluene,filtered once through a Puradisc filter, and spin-coated onto stripedpixel ITO glass to yield a solvent-susceptible layer having a drythickness of 162 nm. Using toluene, the coated layer was selectivelyremoved from portions of the ITO region to provide contact areas forconnecting the receptor to a power supply.

Preparation of Donor

TAPC, TPOB (sublimed), and Ir(ppy)₂(tmhd) (a green emitter) werecombined in a 45:45:10 weight ratio, diluted with chlorobenzene to 1.78%by weight, and allowed to stir for 20 minutes at 70° C. on a hotplate.The resulting solution was filtered once through a Puradisc filter andspin-coated onto a donor film prepared as described in the GeneralPreparation to yield a transfer layer having a dry thickness of 45 nm.

Selective Thermal Transfer of Patterned Emitter Layer

The transfer layer from the donor was imaged onto the receptor by LITIto yield a patterned emitter layer that was in registration with everyother ITO stripe. One laser was used at a power of 4 watts in aunidirectional scan with a triangle dither pattern and frequency of 400KHz. The requested line width was 110 micrometers with a pitch of 330micrometers and the dose was 0.90 J/cm².

Deposition of Non-Patterned Emitter Layer and Deposition of Cathode

A non-patterned emitter layer containing perylene blue dye and atwo-layer cathode were then deposited on the patterned emitter layerfollowing the procedure described in conjunction with Example I for thedeposition of these layers.

Preparation of Control Devices for Example 6

Two control devices were prepared for Example 6. The first controldevice was prepared following the procedure used to prepare Example 6except that during the selective thermal transfer of the transfer layer,the pitch was 165 micrometers which resulted in a pattern that was inregistration with every ITO stripe. The second control device was alsoprepared following the procedure used in conjunction with Example 6except omitting preparation of the donor and thermal transfer of thetransfer layer. Consequently, in the second control device, thenon-patterned emitter layer containing perylene blue dye was disposeddirectly on the solvent-susceptible layer and without an interveningpatterned emitter layer.

Electroluminescence Spectra

The electroluminescence spectra for the device of Example 6 and its twocontrol devices were observed using the procedure described inconjunction with Example 2. The device of Example 6 showed a pattern ofalternating green and blue stripes, the green emission patterncorresponding to the area patterned by the selective thermal transfervia LITI. The first control device showed a pattern of green stripescorresponding to the area patterned by the selective thermal transfervia LITI, and the second control device showed a pattern of blue stripescorresponding to the pattern of ITO stripes.

Example 7

Example 7 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer on a solvent-susceptible layer, and a layercomprising a second emitter is disposed on the patterned emitter layerto provide a non-patterned emitter layer.

Example 7 was prepared by following the procedure described inconjunction with Example 6 except that in the solvent-susceptible layerdeposited on the receptor, 2-mTNATA was replaced by ST 1693.S and thislayer was applied so as to have a dry thickness of 140 nm. Two controldevices for Example 7 were also prepared following the proceduredescribed in conjunction with Example 6 except for the presence, on thereceptor, of the solvent- susceptible layer containing ST 1693.S insteadof 2-mTNATA.

Electroluminescence Spectra

The electroluminescence spectra for the device of Example 7 and its twocontrol devices were observed using the procedure described inconjunction with Example 6. The device of Example 7 showed a pattern ofalternating green and blue stripes, the green emission patterncorresponding to the area patterned by the selective thermal transfervia LITI. The first control device showed a pattern of green stripescorresponding to the area patterned by the selective thermal transfervia LITI, and the second control device showed a pattern of blue stripescorresponding to the pattern of ITO stripes.

Example 8

Example 8 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer on a solvent-susceptible layer, and a layercomprising a second emitter is disposed on the patterned emitter layerto provide a non-patterned emitter layer.

Preparation of Receptor

A solution of ST 755.S was made at 5.0 wt. % in chlorobenzene, allowedto stir for 20 minutes at 70° C. on a hotplate, filtered once through aPuradisc filter, and spin-coated onto striped pixel ITO glass. Thecoated ITO glass was baked for 10 minutes at 80° C. under a nitrogenatmosphere to yield a solvent-susceptible layer having a dry thicknessof 126 nm. Using toluene, the coated layer was selectively removed fromportions of the ITO region to provide contact areas for connecting thereceptor to a power supply.

Preparation of Donor

ST 755.S, TPOB (sublimed), and Ir(btp)₂(tmhd) (a red emitter) werecombined in a 44.26:44.26:11.5 weight ratio, diluted with chlorobenzeneto 1.71% by weight, and allowed to stir for 20 minutes at 70° C. on ahotplate. The resulting solution was filtered once through a Puradiscfilter and spin-coated onto a donor film prepared as described in theGeneral Preparation to yield a transfer layer having a dry thickness of45 nm, after being baked at 80° C. for 10 minutes under a nitrogenatmosphere.

Preparation of Control Devices for Example 8

Two control devices were prepared for Example 8. The first controldevice was prepared by imaging the transfer layer from the donor to thereceptor using one laser at a power of 4 watts in a unidirectional scanwith a triangle dither pattern and frequency of 400 KHz. The requestedline width was 110 micrometers with a pitch of 165 micrometers and adose of 0.90 J/cm², resulting in an imaged pattern that was inregistration with every ITO stripe. A non-patterned emitter layercontaining perylene blue dye and a two-layer cathode were then depositedon the patterned emitter following the procedure described inconjunction with Example 1 for the deposition of these layers.

The second control device was also prepared following the procedure usedin conjunction with Example 8 except omitting preparation of the donorand thermal transfer of the transfer layer. Consequently, in the secondcontrol device, the non-patterned emitter layer containing perylene bluedye was disposed directly on the solvent-susceptible layer and withoutan intervening patterned emitter layer.

Electroluminescence Spectra

The electroluminescence spectra for the device of Example 8 and its twocontrol devices were observed using the procedure described inconjunction with Example 2. The first control device showed a pattern ofred stripes corresponding to the area patterned by the selective thermaltransfer via LITI, and the second control device showed a pattern ofblue stripes corresponding to the pattern of ITO stripes.

Example 9

Example 9 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer on a solvent-susceptible layer, and a layercomprising a second emitter is disposed on the patterned emitter layerto provide a non-patterned emitter layer.

Example 9 was prepared by following the procedure described inconjunction with Example 8, except that in the solvent-susceptible layerthat was deposited on the substrate, ST 755.S was replaced ST 1693.S andthis layer was applied so as to have a dry thickness of 140 nm. Inaddition, the solution of ST 1693.S was made at 6.0% by weight intoluene and allowed to stir for 5 minutes under ambient conditionsbefore being filtered and spin-coated. Two control devices for Example 9were also prepared following the procedure described in conjunction withExample 8 except for the presence of the of ST 1693.S in thesolvent-susceptible layer that was deposited on the receptor instead ofST 755.S.

Electroluminescence Spectra

The electroluminescence spectra for the two control devices wereobserved using the procedure described in conjunction with Example 6.The first control device showed a pattern of red stripes correspondingto the area patterned by the selective thermal transfer via LITI, andthe second control device showed a pattern of blue stripes correspondingto the pattern of ITO stripes.

Example 10

Example 10 illustrates a method of making an electroluminescent deviceaccording to the invention in which transfer layers comprising a firstemitter and a second emitter are selectively thermally transferred to areceptor to form a patterned emitter layer on a solvent-susceptiblelayer, and a layer comprising a third emitter is disposed on thepatterned emitter layer to provide a non-patterned emitter layer.

Preparation of Receptor

A solution of ST 755.S was made at 5.0 wt. % in chlorobenzene, allowedto stir for 20 minutes at 70° C. on a hotplate, filtered through aPuradisc filter, and spin-coated onto striped pixel ITO glass. Thecoated ITO glass was baked for 10 minutes at 80° C. under a nitrogenatmosphere to yield a solvent-susceptible layer having a dry thicknessof 126 nm. Using toluene, the coated layer was selectively removed fromportions of the ITO region to provide contact areas for connecting thereceptor to a power supply.

Preparation of Donor

To prepare a first donor corresponding to the first emitter, ST 755.S,TPOB, and Ir(btp)₂(tmhd) (a red emitter) were combined in a44.26:44.26:11.5 weight ratio, diluted with chlorobenzene to 1.71% byweight, and stirred for 20 minutes at 70° C. on a hotplate. Theresulting solution was filtered once through a Puradisc filter andspin-coated onto a donor film prepared as described in the GeneralPreparation to yield a transfer layer having a dry thickness of 45 nm,after baking in an oven at 80° C. for 10 minutes under a nitrogenatmosphere. A second donor corresponding to the second emitter wasprepared in the same manner but substituting a green emitter, Ir(ppy)₂(tmhd), for the red emitter.

Selective Thermal Transfer of Patterned Emitter Layers

The transfer layer from the first donor was imaged onto the receptor byLITI to yield a patterned emitter layer. One laser was used at a powerof 4 watts in a unidirectional scan with a triangle dither pattern andfrequency of 400 KHz. The requested line width was 110 micrometers witha pitch of 495 micrometers and the dose was 0.90 J/cm². The transferlayer from the second donor was then imaged onto the same receptor byLITI and using the same laser arrangement to provide a patterned emitterlayer comprising first (red) and second (green) emitters. The origin forthe transfer layer containing the green emitter was shifted +165micrometers relative to the origin for the transfer layer containing thered emitter.

Deposition of Non-Patterned Emitter Layer and Deposition of Cathode

A non-patterned emitter layer containing perylene blue dye and atwo-layer cathode were then deposited on the patterned emitter layercomprising the first (red) and second (green) emitters following theprocedure described in conjunction with Example 1 for the deposition ofthese layers.

Electroluminescence Spectra

The electroluminescence spectrum for Example 10 was observed using theprocedure described in conjunction with Example 2 and showed a patternof alternating red, green and blue stripes, the red and green emissionpatterns corresponding to the areas patterned by the selective thermaltransfer via LITI.

Example 11

Example 11 illustrates a method of making an electroluminescent deviceaccording to the invention in which a transfer layer comprising a firstemitter is selectively thermally transferred to a receptor to form apatterned emitter layer on a solvent-susceptible layer, and a layercomprising a second emitter is disposed on the patterned emitter layerto provide a non-patterned emitter layer.

Preparation of Electroluminescent Device

A donor was prepared according to the procedure described in conjunctionwith Example I and the transfer layer was selectively thermallytransferred to a receptor containing a solvent-susceptible layer thatwas prepared according to the procedure described in conjunction withExample 9 to yield a patterned emitter layer. Two lasers were used at apower of 16 watts in a unidirectional scan with a triangle ditherpattern and frequency of 400 KHz. The requested line width was 110micrometers with a pitch of 165 micrometers, and the dose was 0.650J/cm². A non-patterned emitter layer containing perylene blue dye and atwo-layer cathode were then deposited on the patterned emitter layerfollowing the procedure described in conjunction with Example 1 for thedeposition of these layers.

Preparation of Control Device for Example 11

A control device was also prepared following the procedure used inconjunction with Example 11, except omitting preparation of the donorand thermal transfer of the patterned emitter layer. Consequently, thenon-patterned emitter layer containing perylene blue dye was disposeddirectly on the solvent-susceptible layer and without an interveningpatterned emitter layer.

Electroluminescence Spectra

The electroluminescence spectra for the device of Example 11 and itscontrol device were observed using the procedure described inconjunction with Example 2. The device of Example 11 showed a pattern ofalternating yellow and blue stripes, the yellow emission patterncorresponding to the area patterned by the selective thermal transfervia LITI. The control device showed a pattern of blue stripescorresponding to the pattern of ITO stripes.

The complete disclosure of all patents, patent applications, andpublications, and electronically available material cited herein areincorporated by reference. The foregoing detailed description andexamples have been given for clarity of understanding only. Nounnecessary limitations are to be understood therefrom. The invention isnot limited to the exact details shown and described, for variationsobvious to one skilled in the art will be included within the inventiondefined by the claims.

1. A method of making an electroluminescent device comprising:selectively thermally transferring a portion of a transfer layercomprising a first emitter to a receptor to form a patterned emitterlayer comprising the first emitter disposed on the receptor; anddisposing a layer comprising a second emitter on the patterned emitterlayer and the receptor to form a non-patterned emitter layer comprisingthe second emitter.
 2. The method of claim 1 further comprisingselectively thermally transferring, prior to forming the non-patternedemitter layer, a portion of a second transfer layer comprising a thirdemitter to the receptor to form a second patterned emitter layercomprising the third emitter, disposed on the receptor.
 3. The method ofclaim 1 wherein the receptor is an anode, a hole transport layer, a holeinjection layer, an electron blocking layer, a dielectric layer, apassivation layer, a substrate, or a combination thereof.
 4. The methodof claim 1 wherein the non-patterned emitter layer is an undopedelectron transport layer, a doped electron transport layer, an undopedhole blocking layer, a doped hole blocking layer, or a combinationthereof.
 5. The method of claim 1 wherein the receptor is a holetransport layer and is attached to an anode.
 6. The method of claim 5wherein the device further comprises a hole injection layer disposedbetween the hole transport layer and the anode.
 7. The method of claim 1further comprising disposing a cathode on the non-patterned emitterlayer.
 8. The method of claim 1 wherein the receptor issolvent-susceptible.
 9. A method of making an electroluminescent devicecomprising: providing a non-patterned layer comprising a first emitter;and selectively thermally transferring a portion of a transfer layercomprising a second emitter to the non-patterned emitter layer to form apatterned emitter layer comprising the second emitter, disposed on thenon-patterned emitter layer.
 10. The method of claim 9 furthercomprising selectively thermally transferring a portion of a secondtransfer layer comprising a third emitter to the non-patterned emitterlayer to form a second patterned emitter layer comprising the thirdemitter, disposed on the non-patterned emitter layer.
 11. The method ofclaim 9 wherein the non-patterned emitter layer is an undoped electrontransport layer, a doped electron transport layer, an undoped holeblocking layer, a doped hole blocking layer, an undoped electroninjecting layer, a doped electron injecting layer, or a combinationthereof.
 12. The method of claim 9 further comprising disposing an anodeon the patterned emitter layer and the non-patterned emitter layer. 13.The method of claim 12 wherein the device further comprises a holetransport layer, a hole injection layer, an electron blocking layer, ora combination thereof, disposed between the patterned emitter layer andthe anode.
 14. The method of claim 9 wherein the side of thenon-patterned emitter layer opposite the patterned emitter layer isattached to a cathode.
 15. The method of claim 9 wherein thenon-patterned emitter layer is solvent-susceptible.
 16. A method ofmaking an electroluminescent device comprising: providing asolvent-susceptible layer; disposing a patterned layer comprising afirst emitter and a non-volatile component that is the same as ordifferent than the first emitter on the solvent-susceptible layer; anddisposing a layer comprising a second emitter on the patterned layer andthe solvent-susceptible layer to form a non-patterned emitter layercomprising the second emitter.
 17. The method of claim 16 whereindisposing the patterned layer comprises selectively thermallytransferring a portion of a transfer layer comprising the first emitterand the non-volatile component.
 18. The method of claim 16 furthercomprising, prior to forming the non-patterned emitter layer, disposinga second patterned layer comprising a third emitter on thesolvent-susceptible layer.
 19. The method of claim 18 wherein disposingthe second patterned layer comprises selectively thermally transferringa portion of a second transfer layer comprising the third emitter. 20.The method of claim 19 wherein the second transfer layer furthercomprises a non-volatile component.
 21. A method of making anelectroluminescent device comprising: providing a solvent-susceptible,non-patterned layer comprising a first emitter; and disposing apatterned layer comprising a second emitter and a non-volatile componentthat is the same as or different than the second emitter, on thesolvent-susceptible layer.
 22. The method of claim 21 wherein disposingthe patterned layer comprises selectively thermally transferring aportion of a transfer layer comprising the second emitter and thenon-volatile component.
 23. The method of claim 21 further comprisingdisposing a second patterned layer comprising a third emitter on thesolvent-susceptible layer.
 24. The method of claim 23 wherein disposingthe second patterned layer comprises selectively thermally transferringa portion of a second transfer layer comprising the third emitter. 25.The method of claim 24 wherein the second transfer layer furthercomprises a non-volatile component.
 26. An electroluminescent devicecomprising: a solvent-susceptible layer; a patterned layer on thesolvent-susceptible layer, wherein the patterned layer comprises a firstemitter and a non-volatile component that is the same as or differentthan the first emitter; and a non-patterned layer comprising a secondemitter, disposed on the patterned emitter layer and the solventsusceptible layer.
 27. The device of claim 26 wherein the patternedlayer further comprises a third emitter.
 28. The device of claim 26further comprising a second patterned layer disposed on thesolvent-susceptible layer, wherein the second patterned layer comprisesa third emitter.
 29. The device of claim 26 wherein thesolvent-susceptible layer is a hole transport layer, a hole injectionlayer, an electron blocking layer, a dielectric layer, a passivationlayer, or a combination thereof.
 30. The device of claim 26 wherein thenon-patterned emitter layer is an undoped electron transport layer, adoped electron transport layer, an undoped hole blocking layer, a dopedhole blocking layer, an undoped electron injecting layer, a dopedelectron injecting layer, or a combination thereof.
 31. The device ofclaim 26 further comprising an anode attached to the solvent-susceptiblelayer.
 32. The device of claim 31 further comprising a cathode attachedto the non-patterned emitter layer.
 33. The device of claim 31 furthercomprising a hole injection layer, an electron blocking layer, or acombination thereof disposed between the anode and thesolvent-susceptible layer.
 34. The device of claim 32 wherein thecathode is opaque, the anode is transparent, and the device is operableto emit light through the transparent anode.
 35. The device of claim 32wherein the cathode is transparent, the anode is opaque, and the deviceis operable to emit light through the transparent cathode.
 36. Thedevice of claim 32 wherein the cathode is transparent, the devicefurther comprises an opaque substrate attached to the anode, and thedevice is operable to emit light through the transparent cathode. 37.The device of claim 32 wherein the cathode is transparent, the anode istransparent, and the device is operable to emit light through thetransparent cathode and the transparent anode.
 38. The device of claim26 wherein the non-patterned emitter layer is solvent-susceptible.
 39. Amethod of generating light comprising: providing an electroluminescentdevice according to claim 32; and providing a signal to the anode andthe cathode, wherein the signal is operable to address an emitter,following which the emitter emits light.
 40. The method of claim 39wherein the device is an active or passive addressed device.
 41. Themethod of claim 39 wherein the device is a full color display or tunablelighting device.